Shaft and cup dent puller

ABSTRACT

A power-driven dent puller device for the repair of dented sheet metal is described. The device comprises a screw-threaded shaft assembly having a removable self-tapping screw at one end and a drive socket at the other end adapted for driving interconnection with an ordinary air wrench drive mechanism. Cooperative with the screw-threaded shaft assembly is a cylindrical abutment member having an apertured wall at one end for substantially coaxially receiving the screw-threaded shaft assembly and against which a loosely retained washer circumjacent an inner end portion of the screw-threaded shaft assembly abuts in the use of the device. In use, the self-tapping screw is power driven in self-tapping relation through an opening punched in the dented area to be repaired, whereupon the outer end of the cylindrical abutment member will be moved into abutting engagement with the sheet metal being repaired in surrounding relation with respect to the punched opening to pull the dented sheet metal outwardly in the direction of the abutment member.

Iinited States Patent Steinmann, Jr.

[451 .ian.l8,i972

[54] SHAFT AND CUP DENT PULLER [22] Filed: Oct. 28, 1969 [21] Appl. No.: 870,048

Primary Examiner-Charles W. Lanham Assistant Examiner-Gene P. Crosby Attorney-Emest H. Schmidt [57] ABSTRACT A power-driven dent puller device for the repair of dented sheet metal is described. The device comprises a screw threaded shaft assembly having a removable self-tapping screw at one end and a drive socket at the other end adapted for driving interconnection with an ordinary air wrench drive mechanism. Cooperative with the screw-threaded shaft assembly is a cylindrical abutment member having an apertured wall at one end for substantially coaxially receiving the screwthreaded shaft assembly and against which a loosely retained washer circumjacent an inner end portion of the screwthreaded shaft assembly abuts in the use of the device. In use, the self-tapping screw is power driven in self-tapping relation through an opening punched in the dented area to be repaired, whereupon the outer end of the cylindrical abutment member will be moved into abutting engagement with the sheet metal being repaired in surrounding relation with respect to the punched opening to pull the dented sheet metal outwardly in the direction of the abutment member.

sum AND cur DENT FULLER This invention relates to automobile body repair work and is directed particularly to a dent puller attachment device for an air wrench drive mechanism.

In the repair of damaged automotive vehicle bodies, the first step in the reshaping of indented zones is to bring the indented sheet metal as nearly as practicable back into its original shape, that is, into a plane substantially coincident with that of the surrounding undamaged area. While this can usually be easily done in sheet metal body areas to which access can be had from behind, such as in fender, hood and trunk door panel zones, for example, by hammering out indented zones with the use of appropriate dollies, this method is not as readily adaptable to outer door panels and the like to which access from behind can only be had after disassembly of substantial portions of interior structure. To overcome this time-consuming difficulty in the repair of dented exterior door panels and the like to which access to the rear can be had only with difficulty, various methods have been devised for attaching a tool to a dented portion from the outside thereof so that it can be pulled back into substantially the original shape from the outside of the panel. The tools heretofore provided usually comprised a screw-threaded shaft adapted to be force threaded into a small hole punched in the dented zone to be reshaped, and mechanism for pulling outwardly upon the threaded shaft so attached to pull the dented zone back into substantially straightened position. Such tools as have heretofore been devised, however have been found to be deficient in various respects, principally in that they are manually operated and therefore time consuming ,iri use, especially in the repair of elongated dents running substantial distances along the panel to be repaired.

It is, accordingly, the principal object of this invention to provide a novel and improved dent puller of the general character and for use as described above which is power actuated and therefore obviates for the most part the deficiencies of dent pulling tools heretofore devised.

A more particular object of the invention is to provide a dent puller attachment device for use with a compressed air wrench drive as a source of driving power.

Another object of the invention is to provide a dent puller attachment device of the above nature wherein the screw shaft is rotatively power driven and retained in substantially fixed axial disposition with respect to a panel area around the dented zone being operated upon by means of a cuplike abutment member, whereby drawing or pulling out of the indented zone is effected by the forceful riding up thereof along the turning thread of the screw-threaded shaft.

Another object of the invention is to provide a dent puller attachment device of the character described wherein the screw-threaded shaft assembly can readily be assembled to the abutment member during use of the device in repairing a dented body panel area, and wherein the abutment member is provided with an aperture permitting visual observation of the device while in operation so that effective control of the drive power can be exercised.

Yet another object of the invention is to provide a dent puller attachment device of the above nature which will be simple in structure, economical to manufacture, effective in operation and long wearing in use.

Other objects, features and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. In the drawings, wherein like reference numerals denote corresponding parts throughout the several views:

FIG. 1 illustrates, in side view, the screw-threaded shaft assembly embodying the invention, shown separately;

FIG. 2 is a side elevational view of the abutment member embodying the invention, shown separately; and

.FIG. 3 is an end view of the abutment member shown in FIG. 2, as seen from the left-hand end thereon.

Referring now to the drawings in detail, the screw-threaded shaft assembly of FIG. 1 comprises a drive socket portion 1 formed at the outer end with a rectangular socket recess Ia, to interfittingly receive the square device pin of an ordinary compressed air wrench drive unit (not illustrated) and having coaxially secured, at its inner end, a short, externally threaded shank portion 5. An abutment stop member 2, which may be in the form of a hexagonal nut, is fixed, as by welding, at the inner end of the shank portion 5 where it abuts the drive socket portion 1. Circumjacently disposed on the threaded shank portion 5 is an inner flat washer 3 and an outer flat washer 4 of substantially increased diameter with respect to said inner washer. The central openings of the washers 3 and 4 are somewhat greater in diameter than the outer diameter of the shank portion 5 so that said washers are loosely slidable therealong.

Means is provided for replaceably securing a self-tapping screw 7 in coaxial, outwardly extending relation with respect to the outer end of the threaded shank portion 5. To this end, an internally threaded hexagonal capnut 6 is provided, threadable along the outer end of the shank portion 5. The outer end of the capnut 6 is formed with an end wall 60 having a central opening 6b of substantially lesser diameter than that of the interior threaded bore of said capnut to define an interior annular shoulder against which the underside of the hexagonal head portion 7a of a self-tapping screw 7 can be seated. Preferably, the recess at the inner end of the capnut 6 within which the head portion 7a of the self-tapping screw 7 is received is of complementary hexagonal peripheral configuration to prevent rotative slippage of said self-tapping screw upon use of the device as hereinbelow more particularly described. It will be understood that the self-tapping screw 7 can readily be assembled in place, as illustrated in FIG. I, with respect to the remainder of the screw-threaded shaft assembly simply by tightening the capnut 6 upon the outer end of the externally threaded shank portion 5 so that the outer end of said shank portion clampingly abuts against the outer end of the head portion 7a of the self-tapping screw 7. To minimize the possibility of loosening of the capnut 6 upon use of the device, a locknut 6c is threadingly received on the shank portion 5, behind said capnut for use as a jamnut thereagainst.

While I have illustrated and described the screw-threaded shaft assembly of FIG. 1 as being fabricated of standard, readily available parts such as machine nuts, washers and externally threaded cylindrical rod, it will be understood that the socket portion 1, the abutment stop member 2 and the threaded shank portion 5 could just as well be integrally fabricated in quantity production.

Referring now to FIG. 3 of the drawings, illustrating a typical abutment member for cooperative use with the screwthreaded shaft assembly of FIG. I, the same comprises a cylindrical wall portion 8 preferably of steel tubing, against the outer end of which is affixed, such as by welding, a circular abutment plate 8a. As illustrated in FIG. 2, the cylindrical wall portion 8 is formed, near the outer or abutment plate end, with a circular opening 8b communicating with the inner peripheral edge thereof through a symmetrically arranged slot opening of somewhat lesser width than the diameter of said opening. The abutment plate 8a is provided with a radial slot opening 8d having the same width or breadth as that of the slot 8c, and communicating therewith at its outer end. The inner end of the radial slot 8d merges with a semicircular opening 8e concentric with the circular abutment plate 3a.

In the use of my dent puller attachment device, sheet metal dents to be repaired will first be provided with punched openings within and along the zone of deepest indentation, appropriately spaced therein for successive dent-pulling operations as hereinbelow described. These punched openings will be of such diameter as to permit self-tapping of the selftapping screw 7 when screw-threaded therein upon operation of an air wrench drive mechanism. To this end, the screwthreaded shaft assembly of FIG. 1 will be substantially concentrically interfitted within the abutment member of FIG. 2 by passing the self-tapping screw and the capnut 6 down through the circular opening 8b of the abutment member of FIG. 3,

permitting the threaded shank portion 5 to be received substantially concentrically within the radial slot 8d and semicircular opening 8e. When so interfitted, the outer fiat washer 4 will abut against the circular abutment plate 8a so that the outer end of the self-tapping screw 7 extends for a substantial distance beyond the outer peripheral edge of the open end of the cylindrical wall portion 8 of the abutment member. The screw-threaded shaft assembly will be snap fitted, by means of its drive socket portion 1, to an air wrench drive mechanism afier which the tapered end of the self-tapping screw 11 will be applied to one of the punched openings in the sheet metal dented zone to be repaired and power driven to self-tap therein during operation of the air wrench. As the self-tapping screw 7 thus threads itself into the punched opening, it will move forwardly, carrying with it the interfitted abutment member of FIG. 2 until said abutment member, at its outer end, is brought into abutting engagement with a zone of the sheet metal surrounding the dent to be pulled outwardly, whereupon, as a result of continued turning of the self-tapping screw 7, the dented sheet metal surrounding the tapped punched opening will be forcefully drawn or pulled outwardly, riding along the turning spiral thread of the self-tapping screw 7. During this operation, the circular opening 8b of the abutment member will have been so placed as to permit convenient visual observation of the turning of the self-tapping screw and the outward movement of the dented sheet metal in response thereto so that the drive power of the air wrench drive mechanism can be controlled by the operator to effect optimum outward pulling of the dented sheet metal. Once this particular area of sheet metal has been pulled or undented by the desired amount, the air wrench drive mechanism will be reversed to effect withdrawal of the self-tapping screw 7, after which the same procedure will be repeated to pull adjacent dented areas by application to the remaining punched openings.

It will be understood that in the preparation of the dented zone in the sheet metal to be repaired, the punched openings will appropriately spaced along and within the dented area, with respect to the size and depth of the dent, to provide for the best straightening of the sheet metal consistent with the economical use of time involved in making the repair. In this connection it is to be noted that the combinative use of my dent puller attachment device with an air wrench drive permits rapid progression along a series of punched holes in a sheet metal dent to be repaired, so that better work can be performed in a shorter time than with use of manually actuated dent puller devices of the type heretofore devised.

While I have illustrated and described herein only one form in which my invention can conveniently be embodied in practice, it is to be understood that this form is given by way of example only and not in a limiting sense. For example, although I have illustrated a particular size of abutment member for cooperative use with the screw-threaded shaft assembly, it is to be understood that said abutment member could as well be of greater or lesser relative size, both as to length and particularly as to external diameter, to best accommodate for the repair of sheet metal dents having a wide range of dent area. The invention, in brief, comprises all the embodiments and modifications coming within the scope and spirit of the follow ing claims.

What I claim as new and desire to secure by Letters Patent 1. A dent puller attachment device for an air wrench drive comprising, in combination, an elongated shank member, means at one end of said shank member for removably securing a self-tapping screw in coaxial, outwardly extending relation with respect thereto, a socket drive member afi'ixed in coaxial relation with respect to the other end of said shank member, an abutment member circumjacent said shank member and movable therealong between said self-tapping screw securing means and said drive member, abutment stop means at the inner end of said socket drive member for limiting the axial movement of said abutment member, a tubular abutment cup member comprising a peripheral wall portion and an abutment plate portion affixed at one end thereof, said peripheral wall portion and said abutment plate portion having communicating openings permitting the insertion of said shank member in substantially coaxial relation in said abutment cup member.

2. A dent puller attachment device as defined in claim 1 wherein said self-tapping screw securing means comprises a capnut having a central aperture for the projection therethrough of a headed self-tapping screw received within said capnut, said shank member being externally threaded and said capnut being internally threaded for screw-threading on said shank member.

3. A dent puller attachment device as defined in claim 1, wherein said self-tapping screw securing means further comprises a locknut threaded on said shank member behind said capnut.

4. A dent puller attachment device as defined in claim 1, wherein said abutment member circumjacent said shank member is in the form of a substantially flat washer.

5. A dent puller attachment device as defined in claim 4, wherein said abutment stop means at the inner end of said drive socket member comprises a second washer of substantially lesser outer diameter than that of said first-mentioned washer.

6. A dent puller attachment device as defined in claim 1, wherein the peripheral wall portion of said abutment cup member is substantially cylindrical in shape and wherein said abutment plate is of substantially circular configuration.

7. A dent puller attachment device as defined in claim 6, wherein the opening in said peripheral wall portion is substantially circular and wherein the opening in said abutment plate is partially of semicircular configuration of lesser diameter than that of said peripheral wall opening, and concentric with said cylindrical peripheral wall portion. 

1. A dent puller attachment device for an air wrench drive comprising, in combination, an elongated shank member, means at one end of said shank member for removably securing a selftapping screw in coaxial, outwardly extending relation with respect thereto, a socket drive member affixed in coaxial relation with respect to the other end of said shank member, an abutment member circumjacent said shank member and movable therealong between said self-tapping screw securing means and said drive member, abutment stop means at the inner end of said socket drive member for limiting the axial movement of said abutment member, a tubular abutment cup member comprising a peripheral wall portion and an abutment plate portion affixed at one end thereof, said peripheral wall portion and said abutment plate portion having communicating openings permitting the insertion of said shank member in substantially coaxial relation in said abutment cup member.
 2. A dent puller attachment device as defined in claim 1 wherein said self-tapping screw securing means comprises a capnut having a central aperture for the projection therethrough of a headed self-tapping screw received within said capnut, said shank member being externally threaded and said capnut being internally threaded for screw-threading on said shank member.
 3. A dent puller attachment device as defined in claim 1, wherein said self-tapping screw securing means further comprises a locknut threaded on said shank member behind said capnut.
 4. A dent puller attachment device as defined in claim 1, wherein said abutment member circumjacent said shank member is in the form of a substantially flat washer.
 5. A dent puller attachment device as defined in claim 4, wherein said abutment stop means at the inner end of said drive socket member comprises a second washer of substantially lesser outer diameter than that of said first-mentioned washer.
 6. A dent puller attachment device as defined in claim 1, wherein the peripheral wall portion of said abutment cup member is substantially cylindrical in shape and wherein said abutment plate is of substantially circular configuration.
 7. A dent puller attachment device as dEfined in claim 6, wherein the opening in said peripheral wall portion is substantially circular and wherein the opening in said abutment plate is partially of semicircular configuration of lesser diameter than that of said peripheral wall opening, and concentric with said cylindrical peripheral wall portion. 